This invention relates to valves, and more particularly to a one-way or check valve used, for example, in conjunction with a pump.
Check valves are, of course, widely used in a variety of applications. The type of valve to which this invention pertains finds use, for example, in oil well or water well operations where a liquid (in some applications the liquid carries solids) is flowed through a pipe. The liquid normally flows in one direction and, in response to a differential pressure across the valve, it closes to prevent the flow of liquid in the reverse direction.
Check valves of this nature include a housing forming a flow passage, and an annular valve seat is formed on the wall of the passage. A movable valve member (more commonly referred to simply as the valve) is mounted in the passage and controls the flow through the valve. In prior art constructions, the valve member typically includes a metal valve body and an elastomeric seal which engages the seat to close the valve. Problems with this construction are that the seal is usually stretched when mounting it on the valve body, often causing cracks which eventually lead to failure of the seal, and that solid particles may become lodged between the seal and the body and cause failure. Valves have also been provided where the valve body is made in part of metal and in part of plastic, and the elastomeric seal is mounted on one of the two parts. Further, the U.S. Pat. No. 4,860,995 to Rogers shows a valve body including a metal part and a plastic part wherein the plastic part also functions as the elastomeric seal.
All of the foregoing constructions have the disadvantage that the valve member includes two or more separate parts which are fastened together in some manner. As previously mentioned, such valves have disadvantages, particularly when liquids containing solids flow through the valve.
It is a general object of this invention to provide a novel and improved valve member and method of making such a member, which avoids the foregoing problems.